1) Technical Field
The subject invention relates to an optical detection assembly for detecting dispensed material onto a workpiece.
2) Description of the Prior Art
Dispensing systems for applying a material, such as a bead of adhesive, sealant, or caulk, to a workpiece are well known in the automotive industry. The dispensing systems typically include an applicator having a nozzle for applying the material. The material may be applied in a semi-circular bead or any other suitable thickness or configuration. Typical workpieces include door and trim panels, windows, and other such parts.
The bead of adhesive or sealant being disposed, for example onto a door panel, can be used to provide a moisture barrier and/or to reduce the intrusion of debris between the door panels. In order to ensure a complete seal between the panels, the dispensing of the material should be consistently applied. The presence of air bubbles or a reduction in the material supply passing through the nozzle may create a break or gap in the dispensing of the material. Hence, there could be a disruption in the flow rate of material being dispensed so as to produce a discontinuity or deformation of the bead being deposited onto the workpiece. In other words, there may be a significantly sized gap in the continuous bead or the bead may be of insufficient height or cross-section.
Detection devices have been mounted to the dispensing systems to automatically monitor the dispensed material and recognize a gap in the bead. Examples of these detection devices are shown in U.S. Pat. Nos. 4,724,302; 5,264,678; and 5,666,325. These prior art devices include a single or a pair of sensors positioned near the applicator which may accurately detect the presence of the material as the material is being applied to a uniform or planar surface of the workpiece. The prior art devices, however, have difficulty detecting the presence or non-presence of the material along a non-uniform workpiece which may have bends, curves, contours, depressions, and the like. The sensors are not capable of detecting all of these variations.
Accordingly, it would be desirable to have a dispensing system with a detection assembly which can detect dispensed material on virtually any type of contoured workpiece.
The subject invention is a detection assembly for detecting dispensed material. The detection assembly comprises a housing having an outer periphery. A plurality of sensors are mounted to the housing adjacent the outer periphery. An applicator is mounted to the housing for dispensing the material. The detection assembly is characterized by the outer periphery of the housing defining a central opening with the applicator extending through the opening such that the sensors substantially surround the applicator to continuously detect the material being dispensed through the applicator.
The subject invention also includes the method of detecting the material being dispensed upon a workpiece utilizing a robot having an articulated arm with the housing mounted to the arm and the applicator mounted to the housing. The plurality of sensors substantially surround the applicator and are connected to a detector. The method comprising the steps of; dispensing the material through the applicator onto the workpiece; moving the arm along a predetermined path or moving the workpiece past the dispenser; detecting light intensity values reflected from the workpiece and the dispensed material through each of the sensors surrounding the applicator while the arm and/or workpiece moves along the predetermined path; arranging the light intensity values in a predetermined order; and receiving the arranged light intensity values within the detector to continuously detect the presence of the material applied to the workpiece.
The subject invention therefore overcomes the prior art deficiencies outlined above by providing a plurality of sensors substantially surrounding the applicator such that the detection assembly can detect dispensed material on virtually any type of contoured workpiece.